Most so-called less than lethal projectile bodies are actually made from a plastic or molded polymer material. Non-lethal projectile noses are typically made of an elastic foamed polymer or other compliant material like rubber projectiles of different forms usually used by law enforcement. Different projectiles are characterized by the specificity of the used material, such as those described in patent WO95/23952 or U.S. Pat. No. 3,865,038.
For most projectiles, energy transfer occurs at a diameter not far from the initial caliber. A significant part of the energy is lost in recoil, necessitating more initial speed to deliver adequate energy. These characteristics result in injuries at short range shooting ranges.
Most technical versions are built with elastic, or deformable material or structures, like Bean Bags or products made using Patent No. FR9711361 which uses fine divided solid material in an elastic deformable bag sold under the trademark, BLINIZ. These projectiles bring a greater expansion of the impact without tear at usual impact speeds for law enforcement guns. This product represents a significant enhancement over other existing products due to the wide impact area. But the constraint remains very high in the center of the impact for a short time. But these projectiles are highly deformable and are very unstable in both internal and external ballistic phases due to the free particles inside its elastic walls. Therefore, the constraint in the central area of an impact zone remains high and contributes to the transfer to the receptor target for an important part of the projectile kinetic energy which remains concentrated in the center of the impact area. The distribution of kinetic energy by the surface unit remains variable on the impact surface for all known modes of realization. A known way to reduce such central constraints is to add a high level of amortizing and a low density in the forward part that affect ballistic or stability characteristics.
U.S. Pat. No. 6,283,037 adapt the characteristics to lead to the rupture of the elastic bag if the mechanical constraint overcome a defined threshold, this elastic bag is inserted inside external hard foam hull that breaks at impact with some energy absorption.
United States Patent Application Publication No. 2006/027124 use the same idea, encapsulating the bag in a fragile crushable cocoon that breaks at impact. This publication is applicable for shotguns with small caliber (typically less than 25 mm diameter) and the projectile is fully inserted inside a cartridge and is could not be manipulated directly. The major negative point is that such external hull is characterized by a free surface, which unfixed, and as the result such foam couldn't be used completely to absorb shock energy, the obtained result is therefore a rupture of this hull in several fragments when impacting the target. In addition these splits or parts could be harmful, especially when using hard foam or molded with a skin effect like polyurethane.
U.S. Pat. No. 4,823,702 describes a projectile constituted of a grain agglomerate linked inside a breakable polymer matrix and fixed to the external hull on his rear part. The purpose of such fastening is here to maintain the axial position of the internal solid like compound that will divide at impact in divided solids grains, the difference versus patent FR9711361 is here the size and nature of the said grains or parts. Known state of the art allow the shock spreading on a larger surface, but as a matter of fact didn't provide a significant elongation of the impact duration, due to the important density of used materials. At impact, the implied force onto the target rises rapidly in intensity and reaches his maximum before the spreading. The result is important damages usually took place in the central impact area and if the target is strong enough to avoid penetration, the surface area or the force application growth and fade the local effect.
United States Patent Application Publication No. 2004/089186 describes a non penetrating projectile to deliver anesthesia injection that could be used as a non lethal projectile by the use of a pressurized content or a pyrotechnic gas generator that inflate an elastic capacity, the inflation of the said capacity is triggered by a proximity or contact fuse in the projectile forehead. This patent is the application of the well-known car airbags technologies to protect people from injuries during a car crash. The integration in the forward part of the projectile of a proximity fuse or shock detection sensor is simply mater of miniaturization of what is done in a vehicle at impact. It is quite difficult and relatively expansive to industrialize and manufacture in a small caliber projectile. The way the pressurized capacity expand create a gas inflated volume which doesn't participate to spread the material situated rearward, it only amortize the effect of a hard device situated on the rear part to realize a product injection. The description of this said patent, describe a protection of the forward part or nose with a thin or breakable part at impact, this added part is designed to maintain an aerodynamically profile during the flight, but such design may create some wound problem at impact and is certainly a difficult compromise to realize between aerodynamic efficiency and injuring fragment at impact.
Other so-called non lethal projectiles are designed with an elastic polymer foam head, and cope with the problem to find a compromise between density, elasticity and the speed of impact. Usual constraints are to sustain the initial acceleration, the trajectory and the surface at impact to transfer the energy to the target. If the foam is of low density, the speed is decreasing rapidly and the precision is affected, if the foam is elastic and dense, the precision obtained is better but the trauma wound consequences could be worst. A compromise is therefore in the increase of the caliber and at the same time lowering their speed.
Some realizations chose the low-density foam like the EXACTIMPACT ammunition manufactured by Harmor Holding or equivalent projectiles made by others players. These projectiles need high speed to obtain sufficient precision and energy at long range, making them very harmful at low distance, usual use behind 15 meters could make severe injuries and attempt to target life.
There is a need for a projectile that could be precise at 50 meters with less acceleration and aerodynamic deformation and could deliver at this range about 100 Joules without being lethal at short range with an energy up to 200 Joules, such projectile could avoid lethal injuries when it impact vital organs.
Another solution is described in the patent publication 2006/111719, based on a high resilience and high rupture elongation characteristics containing in his forward part a hollow cavity. A technical limitation of this projectile is that there is no crush or fragmentation of material and energy due to air compression do not allow to absorb a sufficient level of energy and only will reduce the maximum impact force of a few percents. There is no duration length enhancement provided with such a realization.
U.S. Pat. No. 3,865,038 is described by Barr to deliver controlled effect in a shotgun ammunition build with an external hard polymer wall containing a powder, liquid or gas. The said external wall delimited rupture lines and reinforced areas in a way to optimize the effect of impact; the elastic and thick forward part of the head is resistant during the impact and could work as a piston to disperse the contained product in radial directions through the broken lines.
Actually, the combined use of kinetic projectile with pyrotechnic payload is quite limited by the mass of the projectile and the injuries due to splitters projection that are usually penetration into biological target.